Biogas – energy from organic waste

What Is Biogas and How It Is Produced?

Biogas is a renewable energy source created through the natural decomposition of organic matter in oxygen-free conditions. This process, known as anaerobic digestion, is carried out by microorganisms that break down materials such as food waste, farm manure, or sewage sludge. In the UK, biogas has emerged as a viable solution for reducing greenhouse gas emissions, supporting energy security, and managing waste more sustainably.

The gas produced is primarily composed of methane and carbon dioxide. It can be used to generate electricity and heat or upgraded into biomethane, which is suitable for injection into the national gas grid or for use as vehicle fuel. A nutrient-rich by-product called digestate remains after the process, which can be used as fertiliser in agriculture.

With the UK’s increasing focus on decarbonisation and the circular economy, biogas systems are playing a critical role in transforming waste into usable, low-carbon energy across rural and urban settings alike.

Environmental Advantages of Anaerobic Digestion

Anaerobic digestion offers a wide range of environmental benefits that support the UK’s climate targets. One of the most significant is the reduction of methane emissions from landfilled organic waste. Methane is a highly potent greenhouse gas, and capturing it through biogas systems is a key mitigation strategy.

Biogas plants also reduce the amount of biodegradable material sent to landfill, helping local authorities meet their landfill diversion targets and lowering environmental risks such as leachate and odour. This is particularly relevant as landfill space continues to decrease and waste processing costs rise.

The use of digestate contributes to more sustainable agriculture. As an organic fertiliser, it reduces dependence on synthetic inputs, improves soil health, and closes the nutrient loop. By returning organic matter to the land, farmers can enhance soil structure and productivity over time.

Moreover, biogas production aligns with national goals set by the UK’s Net Zero Strategy and supports the transition towards a greener energy system. It also plays a role in reducing ammonia emissions, which is important under the UK’s Clean Air Strategy.

Energy Applications of Biogas in the UK

Biogas has a wide range of applications within the UK’s energy landscape. One of the most common uses is in combined heat and power (CHP) systems, where the gas fuels engines that simultaneously produce electricity and thermal energy. This is particularly effective in agricultural settings, where surplus heat can be used for drying grain or heating buildings.

Upgraded biogas, known as biomethane, is increasingly being injected into the national gas grid. In fact, the UK is home to more than 100 biomethane-to-grid plants, many of which are supplying low-carbon gas to homes and businesses. These facilities help reduce the carbon intensity of domestic heating and cooking.

Public transport is also beginning to benefit from biogas. Cities such as Bristol and Nottingham have introduced buses powered by biomethane, produced from food and sewage waste. This contributes to cleaner urban air and more sustainable mobility.

The food and drink industry is another major user of biogas. Companies such as Nestlé and Diageo utilise anaerobic digestion to treat their organic waste, generating energy to power operations and reduce their environmental impact.

The versatility of biogas makes it an ideal solution for decentralised energy generation, aligning with the UK’s ambitions for local energy systems and community-scale renewable projects.

Challenges in Implementing Biogas Projects

Despite its many advantages, the expansion of biogas in the UK faces certain challenges. One of the primary obstacles is financial. The initial cost of installing anaerobic digesters and upgrading systems is considerable, and not all small or medium-scale producers can access sufficient funding without government support.

Policy uncertainty has also hindered growth. While schemes like the Feed-in Tariff (FiT) and Renewable Heat Incentive (RHI) previously offered financial support, these have closed to new applicants. Although the Green Gas Support Scheme (GGSS) has provided some continuity, long-term policy clarity remains essential for investor confidence.

Planning and permitting processes can be slow and complex, especially for plants located near populated areas. Local concerns over odour, traffic, and visual impact may delay or halt development.

Another issue is the variability in waste collection infrastructure. Inconsistent food waste separation across UK councils limits feedstock availability. While separate food waste collections are set to become mandatory in England from 2025, current disparities hamper efficiency in some regions.

Lastly, there is a skills gap in the operation and maintenance of biogas systems. As the industry grows, there is an increasing need for trained professionals in areas such as biological process management, engineering, and plant optimisation.

Addressing these barriers is essential to unlocking the full potential of biogas within the UK’s broader energy and waste strategy.

Types of Organic Waste That Can Be Used

The success of any anaerobic digestion system depends on the quality and availability of its feedstock. In the UK, a variety of organic waste streams are suitable for biogas production, each offering unique advantages.

Agricultural waste is one of the largest contributors. Slurry and manure from cattle, pigs, and poultry are readily available on UK farms, especially in regions like Northern Ireland and the South West of England. These materials are rich in biodegradable content and offer consistent supply.

Food waste from households, restaurants, and food processing facilities is another valuable source. Although only a portion is currently collected separately, upcoming legislation mandating food waste collection will significantly increase availability.

Green waste, such as grass clippings and garden trimmings, can be combined with wetter feedstocks to improve digestion efficiency. However, care must be taken to avoid contamination with plastics or non-organic materials.

The UK’s water industry also plays a key role. Sewage sludge from wastewater treatment plants is routinely digested to produce biogas, which is then used to generate electricity for the plant or exported to the grid.

The diversity of suitable waste sources allows biogas facilities to be tailored to local conditions, reducing transport costs and supporting regional circular economies.

Comparing Biogas with Other Renewable Energy Sources

Biogas holds a unique position among the UK’s renewable energy options. Unlike solar or wind power, which are weather-dependent and variable, biogas provides a steady and dispatchable energy supply. This makes it particularly valuable for balancing electricity grids and supplying base-load energy.

One of biogas’s biggest advantages is its role in waste reduction. It not only generates energy but also processes organic waste, turning it into a usable resource. This dual function is unmatched by other renewables and supports key national priorities around resource efficiency and landfill diversion.

In terms of infrastructure, biogas systems can be integrated into existing energy and waste networks. The UK’s gas grid is already accommodating growing volumes of biomethane, and CHP units can be connected to both private and public energy systems.

However, biogas facilities require more complex operational management compared to solar or wind. Biological processes must be monitored carefully, and the availability of suitable feedstock must be secured over time.

From a cost perspective, biogas projects tend to involve higher upfront investment, but the ability to generate income from multiple streams—energy, fertiliser, and waste treatment—can improve long-term returns.

As the UK looks to diversify its energy portfolio and enhance system resilience, biogas complements intermittent renewables and strengthens the transition to a low-carbon economy.

UK Success Stories in Biogas Production

Several successful biogas projects across the UK highlight the versatility and impact of this renewable technology. These initiatives serve as models for future development, showing how different sectors can benefit from biogas.

The GENeco facility in Bristol processes food waste and sewage sludge to generate electricity and biomethane. The plant powers local homes and businesses and even fuels a fleet of buses through the city’s transport network.

In Norfolk, the Attleborough AD plant produces biomethane from agricultural residues and food waste. The upgraded gas is injected into the national grid and also used as vehicle fuel, reducing emissions from local transport.

Scottish Water uses anaerobic digestion to manage sludge at several of its treatment works. The biogas generated offsets the plants’ energy needs, lowering both carbon emissions and operational costs.

On a smaller scale, many UK farms are using biogas systems to become more energy independent. For example, Wyke Farms in Somerset powers its cheese-making operation entirely with energy from its own anaerobic digester, using waste from dairy production and local crops.

These examples show that biogas can be successfully integrated into urban, industrial, and agricultural contexts, delivering environmental and economic benefits.

Future Outlook for Biogas in the UK

The outlook for biogas in the UK is optimistic, especially as national policies evolve to meet Net Zero targets by 2050. Biogas and biomethane are recognised in the government’s Energy Security Strategy and offer solutions for decarbonising both heating and transport.

The Green Gas Support Scheme provides critical financial support for biomethane injection projects, encouraging wider deployment. However, future policies will need to address smaller-scale systems and offer support for decentralised projects.

There is growing interest in integrating biogas into local energy systems and community-led sustainability efforts. Combined with digital monitoring and smart grid technologies, these systems can deliver energy where it’s needed most, while managing local waste more efficiently.

Technological innovation continues to improve digester efficiency and reduce costs. Modular systems now allow smaller producers to enter the market, broadening the reach of biogas in rural and semi-rural areas.

With separate food waste collection soon to be standard across the UK, feedstock availability is expected to rise sharply. This will make biogas projects even more viable, both environmentally and economically.

In a future defined by climate action, energy resilience, and resource recovery, biogas has the potential to become a cornerstone of the UK’s clean energy infrastructure.

Frequently Asked Questions (FAQ)

1. What types of waste can be used to produce biogas?
Manure, food waste, green waste, crop residues, and sewage sludge are common feedstocks for biogas systems.

2. Is biogas different from biomethane?
Yes. Biogas is raw gas from digestion; biomethane is purified biogas suitable for the gas grid or vehicles.

3. Can biogas power homes and businesses?
Absolutely. Biogas can generate electricity or be upgraded and injected into the grid for domestic and commercial use.

4. Are there UK government incentives for biogas?
Yes. The Green Gas Support Scheme currently supports biomethane injection projects. Other funding varies regionally.

5. How does biogas support the UK’s climate goals?
It cuts methane emissions, replaces fossil fuels, and supports circular resource use—aligning with Net Zero targets.